Correct Answer - D
Correct (A): The reaction occurs in a basic medium.
Correct (R): `MnO_(4)^(ө)` is reduced to `MnO_(2)` in a mild basic medium or neutral medium whereas in an acidic medium, `MnO_(4)^(ө)` is reduced to `Mn^(2+)` and in a strong basic medium, it is reduced to `MnO_(4)^(2-)`.